The following information was provided by the
California Department of Public Health, Radiologic Health Branch (the Department) via email:
On October 29, 2025, a radiation safety officer (RSO) for Tetra Tech BAS, Inc. contacted the Department about a moisture density gauge that was stolen from a temporary storage unit. The gauge was a CPN Model MC-3, S/N M39068922 (10 mCi nominal of Cs-137 and 50 mCi nominal of Am:Be-241). The gauge was stored in a Conex box located at a construction site in San Juan Capistrano, California.
The construction site is secured with fencing and a locked gate. The gauge was last used by Tetra Tech on October 28, 2025. The gauge case was locked with two padlocks, secured with a chain and two pad locks inside the locked Conex box. When the operator arrived at the site the following morning, the gate was open with the lock cut. The operator then discovered the lock on the Conex box was cut and the door open. An inspection of the inside of the Conex box found that the gauge box and miscellaneous equipment were taken from the Conex box. The operator then contacted the RSO and filed a report with the Orange County Sheriff's Department. The licensee is still investigating the incident. The Department will continue to investigate the incident.
CA incident number: 5010-102925
THIS MATERIAL EVENT CONTAINS A 'Less than Cat 3' LEVEL OF RADIOACTIVE MATERIAL
Sources that are "Less than
IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as
moisture density gauges or thickness
gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks. For additional information go to
http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf